Semiconductor device and a method of manufacturing the same

ABSTRACT

Upon the manufacture of a non-leaded type semiconductor device having an encapsulater, and a gate cured resin and air vent cured resins which remain as a result of the exposure of leads and tub-suspension leads to a mounting surface of the encapsulater and the formation of the encapsulater, a groove through which a resin flows, is not provided over the full circumference of a cavity defined in a mold die for forming the encapsulater. A gate and air vents are provided outside an area in which no groove is defined. The flow of the resin between the cavity and each of the gate and air vents is made through a gap or space defined between each of the adjacent leads and each tub-suspension lead. If the leads and the tub-suspension leads are cut at a groove-free place, then the occurrence of resin waste and a resin crack can be restrained because the gate cured resin and the air vent cured resins have their surfaces which are identical to the leads and the tub-suspension leads and flat.

FIELD OF THE INVENTION

[0001] The present invention relates to a technology for manufacturing aresin molded or encapsulation type semiconductor device using a leadframe, and particularly to a technology effective for application to themanufacture of a semiconductor device wherein external electrodeterminals (leads) are exposed to the mounting surface side as in an SON(Small Outline Non-Leaded Package) and a QFN (Quad Flat Non-LeadedPackage).

BACKGROUND OF THE INVENTION

[0002] A resin encapsulation type semiconductor device makes use of alead frame upon its manufacture. The lead frame is fabricated by forminga metal plate as a desired pattern by punching using a precision pressor etching. The lead frame has a support portion called a “tub or thelike” for fixing a semiconductor chip, and a plurality of leads whoseleading ends (internal ends) face the periphery of the support portion.The tub is supported by tub-suspension leads which extend from a frameportion of the lead frame.

[0003] When the resin encapsulation type semiconductor device isfabricated through the use of such a lead frame, the semiconductor chipis fixed to the tub of the lead frame, and electrodes of thesemiconductor chip and leading ends of the leads are connected to oneanother by conductive wires. Afterwards, the lead internal-end sideincluding the wires and the semiconductor chip is sealed with aninsulating resin to thereby form an encapsulater (package). Further, anunnecessary lead frame portion is removed by cutting, and the leads andtub-suspension leads protruding from the package are cut. Each of theleads is brought to a flat state or processed into a predeterminedshape.

[0004] As technologies for solving a problem as to a transfer mold forforming a resin encapsulation package, there are known technologiesdescribed in Unexamined Patent Publication Nos. Hei 5(1993)-326799,2000-61989 and Hei 5(1993)-299455, for example.

[0005] Although a resin injection hole (gate) is not illustrated in thedrawing in the above technologies, the prior art set forth as a premisehas described that the resin injection hole is provided in a lower mold.Accordingly, a resin (called “gate cured resin”) cured at a gate portionextends on one surface side of a lead frame so as to have apredetermined height.

[0006] Unexamined Patent Publication No. 2000-61989 has disclosed thetechnology of separating a runner from a molded plastic package withbeing flush with the package upon a transfer mold process. Namely, atransfer mold die has a movable gate lowered so as to make contact withthe plastic package formed at a resin inlet for the cavity on the sameplane as the plastic package before the resin is cured after having beeninjected in the cavity. Accordingly, the runner can be cut on a flushbasis with the plastic package.

[0007] The same reference has described that when the resin cured withinthe runner is removed, the resin cured at the runner portion remains ateach edge of the plastic package, and a bottleneck is produced in thesubsequent lead formation and trimming process due to such a remainder.Problems will be quoted from the same reference and described below.

[0008] (1) Damage is put on the trimming of each lead and the formationof a die, and manufacturing yields and a production throughput arereduced. It is necessary to repair or fix up an expensive die.

[0009] (2) There is a possibility that upon lead trimming and formingprocesses, the plastic package will be peeled off from the lead frame,thereby causing a problem about the reliability of a completed product.

[0010] (3) The adhesion of the remainder or remaining materials to theplastic package as it is will lead to a serious result. Describedtypically, a check is made to respective packages and all the remainingmaterials are manually removed. Therefore, personnel costs increase anda manufacturing throughput is reduced.

[0011] According to the present technology, runner's fragments are notleft behind with being attached to the plastic package even after thetransfer mold. Further, the runner can be detached from the molded leadframe. Thus the work of manually removing the remainder becomesunnecessary. It is also possible to avoid damage to the trimming of eachlead and a lead forming instrument due to the remainder as well as toavoid damage to a packaged semiconductor device.

[0012] The present technology shows the technical idea that since theremainder of the resin produces a bottleneck in the trimming processsuch as the bending of each lead, the occurrence of the remainder in thelead frame is avoided even after the removal of the runner. The presenttechnology has no description about the cutting of leads at a gateportion, i.e., a basal portion of the package and makes little mentionof such a problem.

[0013] Unexamined Patent Publication No. Hei 5(1993)-299455 describesthe technology of thinning a gate in stepped form in advance at a baseof a resin encapsulated portion so that when a resin portion cured at agate portion for forming the resin molded portion is separated from apackage, a gate residual is not much left on a placed piece or fragment,and causing a gate cured resin to remain on the placed piece thinner orshorter upon removal of the gate cured resin.

[0014] The present technology does not show the idea of cutting aplaced-fragment portion causing the remainder of the gate.

[0015] On the other hand, as one resin encapsulation type semiconductordevice fabricated using a lead frame, there is known a non-leaded typesemiconductor device such as an SON, a QFN or the like adopted or takenas a semiconductor device structure wherein one surface of the leadframe is single-sided molded to thereby form a package, and leadscorresponding to external electrode terminals are exposed to themounting surface side of the package, thereby avoiding the intentionalprotrusion of the leads from the peripheral surface of the package.

SUMMARY OF THE INVENTION

[0016] In terms of a size reduction in semiconductor device, theprevention of bending of leads corresponding to external electrodeterminals, etc., a non-leaded type semiconductor device such as asingle-sided molded SON or QFN has been used.

[0017] Since the outer shape of the non-leaded type semiconductor deviceis principally determined depending on a resin encapsulater (package)and a lead cutting castle or castled extension formed on its periphery,the semiconductor device can be reduced in size as compared with asemiconductor device of such a type that leads are placed on theperiphery of a package, generally called a “QFP (Quad Flat Package)” oran SOP (Small Outline Package)”. The lead cutting castle or castleextension is produced by ensuring an area for applying a die between acutting-plane line and a package when the leads are cut by punches, andis formed with a width of about 0.1 mm in the embodiment of the presentspecification, for example.

[0018] Problems about the manufacture of the conventional single-sidedmolded non-leaded type semiconductor device will now be explained.

[0019] A description will first be made of one in which a resinencapsulater (package) is formed on one surface side of a lead frame bya transfer mold with the manufacture of QFN as an example.

[0020]FIG. 31 is a plan view showing a resin encapsulater formed by atransfer mold and a unit lead frame pattern. As shown in the samedrawing, a lead frame 1 has a structure having a frame portion 2 shapedin the form of a rectangular frame, a plurality of leads 3 extendinginwardly from inside the respective sides of the frame portion 2, andtub-suspension leads 4 (only one tub-suspension lead is shown in thedrawing) which respectively extend inwardly of the frame portion fromthe four corners of the frame portion 2 and support a central tub (notshown). A resin encapsulater (package) 5 is formed in a central portionof a unit lead frame pattern 6, and leading end portions (internal endportions) of the respective leads 3 extend within the package 5. Lowersurfaces of the leads 3 are exposed from the package 5. The exposed leadportions serve as external electrode terminals for surface mounting whena semiconductor device is brought about.

[0021] Although not illustrated in the drawing, a semiconductor chipfixed onto the tub is placed within the package 5. Further, electrodesof the semiconductor chip and inner ends of the leads 3 are electricallyconnected to one another by conductive wires.

[0022] Upon a transfer mold, a gate (G) is located in one corner(corresponding to the upper right corner in FIG. 31) of the lead frame1. A resin is injected into a cavity of a mold die through the gate tothereby form the corresponding package 5. At this time, air lying withinthe cavity escapes from air vents (E) located in the remaining threecorners of the lead frame 1 to the outside of the mold die. Thus, theresin enters even the gate and the air vents and hence the resin atthese portions is also cured by resin's curing. The resin cured at thegate portion will be referred to as a “gate cured resin 7” below. Theresins cured at the air vent portions will be called “air vent curedresins 9”.

[0023] The package 5 shaped in rectangular form is generally chamferedas shown in FIG. 31 to have slopes 8 in such a way as to avoid thelacking of cornered portions (corners). The slopes 8 are large in gateportion and small in air vent portions.

[0024] After the transfer mold, the resin cured inside each runner forguiding the resin is removed when the curing of the resin is finished.FIG. 31 shows a state in which a runner cured resin or the like isremoved and is a diagram showing that the gate cured resin 7 and the airvent cured resins 9 remain.

[0025]FIG. 32 is a side view typically showing the lead frame 1, package5, air vent cured resins 9, runner cured resin 10 and gate cured resin7. FIG. 33 is a typical cross-sectional view showing the lead frame 1,tub-suspension leads 4, package 5 and gate cured resin 7 or the like. Asshown in FIG. 32, the resin cured at the gate portion upon removal ofthe runner cured resin 10 is formed integrally with the package 5.Therefore, the resin will break in the course thereof and a gate curedresin 7 of a chevron or mounting type as viewed from the side remains.Namely, as the gate cured resin 7 is kept away from the package 5, thethickness thereof becomes thick and its leading end is brought to abroken state.

[0026] Thus, even when the gate cured resin 7 is set to such a shapethat its thickness becomes thick as it is distant from the package, andis designed in such a manner that the gate cure resin is preferablybroken in the vicinity of the package upon breakage and removal of thegate cured resin, the gate cured resin cannot be prevented perfectlyfrom remaining, and the size and shape of the produced remaining curedresin are made in various ways.

[0027] As shown in FIG. 33, the cured resins remain on both sides of thetub-suspension lead 4 as indicated by dots. Namely, upon the transfermold, spaces defined by parting surfaces of upper and lower molds of amold die and the tub-suspension lead 4 and leads 3 adjacent thereto bothlocated at the gate portion are formed as spaces which communicate withthe gate. The cured resins having entered the spaces correspond to thecured resin portions indicted by the dots. This cured resin portions aregenerally called resin burrs 11. The thickness of the each resin burr 11is identical to that of each lead 3 in a state in which the partingsurfaces of the upper and lower molds of the mold die are closely bondedto the observe and reverse sides of the lead frame.

[0028] However, when a gap is defined between each of the partingsurfaces and the lead frame where the above package is clamped betweenthe parting surfaces of the upper and lower molds of the mold die andthe lead frame, the resin enters into the gap and so-called resinflashes occur in each lead surface or the like. In the resin-flashgenerated state, the thickness of each resin burr 11 becomes thickerthan that of each lead.

[0029] After the transfer mold, the leads 3 and tub-suspension leads 4both protruding from the periphery of the package are cut at theperipheral edge of the package 5, whereby the corresponding non-leadedtype semiconductor device (QFN) is manufactured. When, at this time, thesizes of the gate cured resin 7 and each air vent cured resin 9 are toolarge to accommodate or hold them in the lead cutting castle, the gatecured resin 7 and the air vent cured resins 9 are also cut upon leadcutting.

[0030]FIG. 34 is a typical view showing the situation in which a gatecured resin 7 and air vent cured resins 9 are cut by a die 15 andpunches 16 together with each tub-suspension lead 4. The cutting ofleads 3 is also carried out by a die and punches each having a similarstructure.

[0031] However, when the gate cured resin 7 remains at one side of apackage as shown in FIG. 34, it is essential that the gate cured resin 7is cut while the die 15 is being applied to the mounting surface sidecontrary to the normal lead cutting. This is because since the flatnessof each lead surface on the package side is lost due to the presence ofthe gate cured resins 7, and the remaining amounts thereof are alldifferent, the die 15 cannot be stably applied to each lead.

[0032] It turned out that since the gate cured resin 7 takes such ashape as to protrude toward its corresponding punch 16 as describedabove, the gate cured resin 7 firstly contacts the punch 16 and therebystress is applied to the punch 16 upon cutting as shown in FIG. 35,whereby breakage, cracks and chipping are developed therein by stressconcentration and resin waste is frequently produced.

[0033] It has been found that the resin waste 17 is spattered over theperiphery and is thereby attached not only to other lead frame portionsbut also to surfaces related to the cutting of the die 15 and punches 16and cut surfaces of the gate cured resin 7 and tub-suspension lead 4 asshown in FIG. 34. Namely, the resin waste is produced by (1) cuttingaway the resin in fine form when the punches are applied to the gatecured resins as described above and (2) rubbing the punches and theircut surfaces against each other when the punches are returned to theirpredetermined positions after their cutting. Further, the resin wastedrops out even by vibrations at the carrying of a product, contaminatesa cutting die and is re-attached to other product portions.

[0034] In the non-leaded type semiconductor device, there is a fear thatsince each lead surface exposed to the back of the package is brought tothe external electrode terminal surface so as to serve as a mountingsurface, an electrically-isolated state occurs in a mounted state whenthe insulative resin waste is attached or crimped to the surface,thereby interfering with a stable operation of the semiconductor device.

[0035] When the gate cured resin is much cracked upon its cutting, acrack enters even into the package, thereby causing a reduction inmoisture resistance and degradation of reliability.

[0036] If a method of applying the die 15 to the mounting surface sideof each lead with a cutting-plane line interposed therebetween andcutting the leads by the punches 16 from the side opposite to themounting surface is adopted as shown in FIG. 34, then cut burrs occur inthe mounting surface of each lead, thereby losing the flatness of themounting surface and degrading reliability.

[0037] A non-leaded type semiconductor device has heretofore beenfabricated according to a method shown by such a flowchart as shown inFIG. 36. The non-leaded type semiconductor device is manufactured viarespective process steps of Steps 201 through 207. Namely, after thecommencement of work, the semiconductor device is fabricated via therespective process steps of chip bonding (S201), wire bonding (S202),molding (S203), gate pre-cutting (S204), plating (S205), pinch-cut bycomposite cut molding (S206), and lead tip cutting (S207), andthereafter the work is finished.

[0038] In the present manufacturing method, the gate precutting (S204)is carried out before the plating step, and each gate-portiontub-suspension lead is punched out to a predetermined length. Therefore,even if resin waste occurs, the resin waste is removed by cleaningcorresponding to processing subsequent to the plating. Thus, a problemabout the above-described resin waste little arises.

[0039] However, the present manufacturing method is accompanied by adrawback that as a cutting process executed by a press machine, the gatepre-cutting (S204), the pinch-cut (S206) by composite cut molding, andthe lead tip cutting (S207) are carried out twice, thereby increasingthe manufacturing cost of a semiconductor device.

[0040] Thus the present applicant adopts a manufacturing method ofachieving a reduction in manufacturing cost with the press machine-basedcutting process as one. FIG. 37 is a flowchart using the presentmanufacturing method.

[0041] A non-leaded type semiconductor device is manufactured viarespective process steps of Steps 301 through 307. Namely, after thecommencement of work, the semiconductor device is fabricated via therespective process steps of chip bonding (S301), wire bonding (S302),molding (S303), plating (S304), gate crush by composite cut molding(S305), pinch-cut (S306) and lead tip cutting (S307), and thereafter thework is completed.

[0042] A composite cut mold is attached to one press machine. Underintermittent motion of a lead frame and a cutting operation based oncomposite cut molding, the cutting (corresponding to the gate crush forcutting one point in linear form) of a gate portion and tub-suspensionleads thereof, pinch-cutting for cutting remaining tub-suspension leadsused to support a package, and lead tip cutting for cutting all theleads at the basal portion of the package are executed to complete asemiconductor device, and thereafter the work is finished.

[0043] FIGS. 38(a) and 38(b) are respectively typical views showing agate crush operation. In a manufacturing method using gate crush,processing is done in a state in which a package 5 is placed on a lowersurface of a lead frame 1.

[0044] Namely, a die 15 is placed on the upper side of the lead frame 1.A punch 16 goes up from its lower side to cut a gate cured resin 7 andeach tub-suspension lead 4 extending together with the gate cured resin7. The punch 16 serves like a knife edge without having a structure forcutting them to a predetermined length and simply cuts the gate curedresin 7 and each tub-suspension lead 4. The tub-suspension lead 4 isbent as shown in FIG. 38(a) under the post-cut moving operation of thepunch 16. Resin waste 17 is produced even upon the cutting of the gatecured resin 7 and the tub-suspension lead 4.

[0045] Owing to the execution of such gate crush processing, the cuttingof the gate cured resin and each tub-suspension lead thereat atpinch-cutting (S306) become unnecessary, and the produced amount ofresin waste can be reduced. An advantage is brought about in that it ispossible to reduce a resin crack produced in the gate portion and a cutfailure in tub-suspension lead.

[0046] However, it has been found that in the case of the present gatecrush, the cut resin surface and the die are rubbed against each otherwhen the cut type (die) is opened as shown in FIG. 38(b), so that resinwaste is spattered, thereby causing adhesion to each lead surface. Anarrow in FIG. 38(b) is used to indicate the situation in which the resinwaste 17 is spattered upon die opening to thereby adhere onto each lead(while the lead corresponds to the tub-suspension lead in the drawing,unillustrated leads are also arranged on this surface of the package 5).

[0047] An object of the present invention is to provide a technologywherein when a gate cured resin and air vent cured resins are cut uponthe manufacture of a non-leaded type semiconductor device fabricated bya single-sided mold, resin waste is restrained from occurring to therebyprevent the attachment of the resin waste to external electrodeterminals.

[0048] Another object of the present invention is to provide atechnology wherein when a gate cured resin and air vent cured resins arecut upon the manufacture of a non-leaded type semiconductor devicefabricated by a single-sided mold, a resin crack is retrained fromoccurring to thereby prevent a reduction in moisture resistance of thesemiconductor device and the occurrence of a failure in outwardappearance thereof.

[0049] The above, other objects and novel features of the presentinvention will become apparent from the description of the presentspecification and the accompanying drawings.

[0050] Summaries of typical ones of the inventions disclosed in thepresent application will be described in brief as follows:

[0051] (1) There is provided a semiconductor device which has anencapsulater comprising an insulating resin, leads and tub-suspensionleads exposed to a mounting surface of said encapsulater and a gatecured resin and air vent cured resins which remain as a result to formsaid encapsulater, and wherein each of the gate cured resin and the airvent cured resins exists in a portion between each tub-suspension leadand each lead with a thickness identical to or smaller than thethickness of each of resin burrs.

[0052] Such a semiconductor device is manufactured by the followingmanufacturing method.

[0053] There is provided a method of manufacturing a semiconductordevice, comprising a step for preparing a lead frame having a frameportion, a plurality of leads which protrude inwardly of the frameportion from the frame portion, and a plurality of tub-suspension leadswhich protrude inwardly of the frame portion from the frame portion andsupport a tub at leading end portions thereof; a step for fixing asemiconductor chip to one surface of the tub; a step for electricallyconnecting electrodes of the semiconductor chip and the leads; a stepfor covering the semiconductor chip and the leads with an encapsulatercomprising an insulating resin and exposing the leads and thetub-suspension leads to a mounting surface of the encapsulater; and astep for cutting the leads and the tub-suspension leads; and wherein avertical space defined by only the sides of the leads and thetub-suspension leads is used as a resin flow path to form theencapsulater, and the leads and the tub-suspension leads are cut at aresin portion cured in the vertical space defined by only the sides ofthe leads and the tub-suspension leads.

[0054] Further, a gate provided in a mold die is provided outside thevertical space defined by only the sides of the leads and thetub-suspension leads, and a resin passes through the gate and flowsthrough the vertical space to thereby form the encapsulater. Inaddition, air vents defined in the mold die are provided outside thevertical space defined by only the sides of the leads and thetub-suspension leads, and the resin passes through the vertical spaceand goes through the air vents.

[0055] According to the means of (1) referred to above,

[0056] (a) The cutting of leads and tub-suspension leads that protrudefrom the periphery of an encapsulater (package), and the cutting of gatecured resins and air vent cured resins produced upon the formation ofthe package are performed at portions respectively identical inthickness and whose front and back are flat. Thus, they can be cut bypunches and a die without partly applying an on-cutting stress on thegate cured resins and air vent cured resins in a large way. It istherefore possible to reduce the occurrence of resin waste to a largeextent as compared with the conventional cutting method and restrain theoccurrence of a resin crack.

[0057] (b) Since the resin waste can be restrained from occurring, theattachment and crimping of the resin waste to lead surfaces serving asexternal electrode terminals due to the spattering of the resin waste,and the occurrence of flaws caused by the crimping can be restrained. Itis also possible to ensure solderability at mounting and enhancemounting yields. Furthermore, the reliability of the mounting orimplementation of a nonleaded type semiconductor device can be improved.

[0058] (c) Since a matrix type lead frame takes a structure wherein unitlead frame patterns are vertically and horizontally arranged in line,the prevention of the spattering of the resin waste results in theprevention of contamination of the resin waste on each unit lead framepattern around a predetermined unit lead frame pattern, wherebyproduction yields can be improved to a great extent.

[0059] (d) Since the occurrence of the resin waste can be restrained,the contamination caused by the cut-die's resin waste can be preventedfrom occurring, and the availability factor of a press machine formounting a cut die can be improved.

[0060] (e) Since the gate cured resins and air vent cured resins aroundthe package are rendered integral with resin burrs between adjacentleads or those between tub-suspension leads and leads and are identicalto the resin burrs in obverse and reverse sides, it is difficult tovisually confirm the gate cured resins and air vent cured resins on theperiphery of the package of the non-leaded type semiconductor device.Thus, the semiconductor device is look good and preferable even in outerappearance, and increases in commodity property.

[0061] (f) The manufacturing cost of a semiconductor device can bereduced in terms of productivity and an improvement in yield.

BRIEF DESCRIPTION OF THE DRAWINGS

[0062]FIG. 1 is a typical plan view showing a lead frame portionsingle-sided molded by a method of manufacturing a semiconductor deviceaccording to one embodiment (first embodiment) of the present invention;

[0063]FIG. 2 is a front view illustrating the semiconductor deviceaccording to the first embodiment;

[0064]FIG. 3 is a plan view depicting the semiconductor device accordingto the first embodiment;

[0065]FIG. 4 is a bottom view showing the semiconductor device accordingto the first embodiment;

[0066]FIG. 5 is a cross-sectional view taken along line B-B of FIG. 3;

[0067]FIG. 6 is a cross-sectional view taken along line C-C of FIG. 3;

[0068]FIG. 7 is a cross-sectional view showing the state of mounting ofthe semiconductor device according to the first embodiment;

[0069]FIG. 8 is a flowchart for describing the method of manufacturingthe semiconductor device according to the first embodiment;

[0070]FIG. 9 is a plan view showing a lead frame employed in themanufacturing method of the semiconductor device according to the firstembodiment;

[0071]FIG. 10 is a plan view depicting a unit lead frame pattern portionof the lead frame;

[0072]FIG. 11 is a plan view showing a state in which a semiconductorchip is fixed to the lead frame, and electrodes of the semiconductorchip and lead inner ends are connected to one another by wires inaccordance with the manufacturing method of the semiconductor deviceaccording to the first embodiment;

[0073]FIG. 12 is a plan view illustrating a state in which a package isformed on one surface of the lead frame by means of a single-sided moldin accordance with the manufacturing method of the semiconductor deviceaccording to the first embodiment;

[0074]FIG. 13 is a cross-sectional view showing a state in which apackage is formed on one surface of a lead frame in accordance with themanufacturing method of the semiconductor device according to the firstembodiment;

[0075]FIG. 14 is a plan view illustrating the correlation between acavity, a resin flow passage or path and a lead frame formed in thesingle-sided mold by a mold die;

[0076]FIG. 15 is a plan view showing a lead frame formed by cuttingtub-suspension leads and a gate cured resin or an air vent cured resinplaced on both sides of the tub-suspension leads in accordance with themanufacturing method of the semiconductor device according to the firstembodiment;

[0077]FIG. 16 is a typical view illustrating a state in which the gatecured resin or the like is cut;

[0078]FIG. 17 is a typical plan view showing a cutting die for cuttingthe gate cured resin or the like;

[0079]FIG. 18 is a typical cross-sectional view depicting the cuttingdie for cutting the gate cured resin or the like:

[0080]FIG. 19 is a plan view showing the lead frame from which leadsextending along an X direction are cut in accordance with themanufacturing method of the semiconductor device according to the firstembodiment;

[0081]FIG. 20 is a typical view illustrating a state in which the leadsextending along the x direction are cut;

[0082]FIG. 21 is a typical plan view depicting a cutting die for cuttingthe leads extending along the X direction;

[0083]FIG. 22 is a plan view showing a semiconductor device obtained bycutting leads extending along a Y direction in accordance with themanufacturing method of the semiconductor device according to the firstembodiment, and a remaining lead frame portion;

[0084]FIG. 23 is a typical view illustrating a state in which the leadsextending along the Y direction are cut;

[0085]FIG. 24 is a typical plan view depicting a cutting die for cuttingthe leads extending along the Y direction;

[0086]FIG. 25 is a cross-sectional view showing another semiconductordevice manufactured by using a flat lead frame wherein leads, a tub andtub-suspension leads are disposed on the same plane in the firstembodiment;

[0087]FIG. 26 is a bottom view of another semiconductor device shown inFIG. 25;

[0088]FIG. 27 is a typical cross-sectional view illustrating a transfermold state obtained according to a method of manufacturing asemiconductor device showing another embodiment (second embodiment) ofthe present invention;

[0089]FIG. 28 is a typical plan view showing a lead frame single-sidedmolded in accordance with the method of manufacturing the semiconductordevice according to the second embodiment;

[0090]FIG. 29 is a typical cross-sectional view illustrating a state inwhich a gate cured resin and an air vent cured resin, and tub-suspensionleads overlapping with these are cut in accordance with the method ofmanufacturing the semiconductor device according to the secondembodiment;

[0091]FIG. 30 is a typical plan view showing a lead frame portionsingle-sided molded by a method of manufacturing a semiconductor deviceaccording to a further embodiment (third embodiment) of the presentinvention;

[0092]FIG. 31 is a plan view illustrating a conventional lead frame inwhich a package is formed on one surface thereof by a transfer mold;

[0093]FIG. 32 is a typical side view depicting the lead frame;

[0094]FIG. 33 is a typical cross-sectional view showing a gate curedresin, resin burrs, etc. of the lead frame;

[0095]FIG. 34 is a typical view showing a state in which a conventionaltub-suspension lead, and a gate cured resin and an air vent cured resinoverlapping with the tub-suspension lead are cut;

[0096]FIG. 35 is a typical view illustrating a state in which theconventional tub-suspension lead and the gate cured resin overlappingwith the tub-suspension lead are cut;

[0097]FIG. 36 is a flowchart for describing a method of manufacturing aconventional non-leaded type semiconductor device;

[0098]FIG. 37 is a flowchart for describing a method of manufacturing anon-leaded type semiconductor device including a gate crush processstep; and

[0099]FIG. 38 is a typical view illustrating the gate crush operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0100] Preferred embodiments of the present invention will hereinafterbe described in detail with reference to the accompanying drawings.Incidentally, ones each having the same function are respectivelyidentified by the same reference numerals in all the drawings fordescribing the embodiments of the present invention, and theirrepetitive description will therefore be omitted.

[0101] (First Embodiment)

[0102]FIGS. 1 through 24 are respectively diagrams related to a methodof manufacturing a semiconductor device showing one embodiment (firstembodiment) of the present invention.

[0103] QFN showing one example of a non-leaded type semiconductor devicemanufactured by the method of manufacturing the semiconductor deviceshowing the first embodiment will first be explained. FIG. 2 is a frontview of the semiconductor device, FIG. 3 is a plan view thereof, FIG. 4is a bottom view thereof, FIG. 5 is a cross-sectional view taken alongline B-B of FIG. 3, and FIG. 6 is a cross-sectional view taken alongline C-C of FIG. 3, respectively.

[0104] In the QFN type semiconductor device 20, a sealing body orencapsulater (insulating sealing body: package) 5 comprises a flatquadrangular or square body (rectangular body) as shown in FIGS. 2through 4. Angular portions (corners) of the sealing body 5 is chamferedto form slopes 8. One of the slopes 8 is large and serves as a resininjection point or portion through which a resin is injected, uponformation of the package 5. Other three slopes 8 become small and serveas air vent portions from which air escapes upon formation of thepackage 5.

[0105] As shown in FIGS. 2, 5 and 6, the package 5 has sides whichrespectively serve as inclined surfaces formed so as to be easy to comeoff or escape from a mold die when the package 5 is formed by a transfermold method. Accordingly, an upper surface 22 of the package 5 issmaller than the size of a mounting surface 21 formed as a lower surfaceeven in the case of any of the drawings referred to above.

[0106] Leads 3 are exposed from the reverse side or back of the package5, i.e., the peripheral edges of the mounting surface 21. The leads 3are disposed at its respective sides at predetermined pitches, forexample. The four corners of the package 5, i.e., tub-suspension leads 4are exposed at or from the peripheral edges of the mounting surface 21,which are associated with the respective centers of the slopes 8.

[0107] As shown in FIGS. 5 and 6, the leads 3 slightly protrudes outsidefrom a rising edge Sa of the package 5 with respect to the surfaces ofthe leads 3 and tub-suspension leads 4, which are covered with thepackage 5, i.e., covered surfaces 3 a and 4 a. This serves as areceiving portion of a die upon cutting the leads 3 and thetub-suspension leads 4 and is less than or equal to 0.1 mm, for example.While resin burrs 11 exist between the respective leads 3 and betweenthe tub-suspension leads 4 and the leads 3, the resin burrs 11 are alsocut by the die and punch. Therefore, the edges of the resin burrs 11 andthe leading edges or tips of the leads 3 and tub-suspension leads 4 arelinearly formed without irregularities at the peripheral edge of thepackage 5.

[0108] On the other hand, when a transfer mold is used to form thepackage 5, the resin enters or pours into any of the resin injectionportion and air vent portions, and they are cured upon a resin curingprocess, whereby a gate cured resin 7 and an air vent cured resin 9 areformed.

[0109] While the resin injection portion (gate: G) is described later inthe semiconductor device manufacturing method in the first embodiment,it is formed by a space (equivalent to a vertical space corresponding tothe lead 3 and the tub-suspension lead 4) between the tub-suspensionlead 4 and the leads 3 disposed on both sides thereof over apredetermined length (a) at the edge portion of the package 5 as shownin FIGS. 1(a) and 1(b). This is defined as a space which does not extendout beyond the thickness of the tub-suspension lead 4 and that of thelead 3. Thus, the thickness of the resin cured at the gate portionhaving the length (a), i.e., the thickness of the gate cured resin 7coincides with the thickness of the lead 3 or the tub-suspension lead 4or smaller than that thereof. The thickness of the gate cured resin 7becomes identical to that of each resin burr 11 formed between theadjacent leads 3. Therefore, the front and back sides thereof are bothbrought to flat surfaces respectively. Since the leads 3 and thetub-suspension leads 4 are cut within a region for the length (a), atrace of the gate cured resin 7 is not prominent as compared with theresin burrs 11 in the semiconductor device 20 of the first embodiment 1while it is designated at reference numeral 7 in FIGS. 3 and 1(a).

[0110] Since, however, a gate groove or trench is provided outside thelength (a) as a groove in the mold die, the gate cured resin 7 protrudesoutside the length (a) beyond the thickness of the lead 3 in a state inwhich the lead frame 1 shown in FIGS. 1(a) and 1(b) is shown. The gatecured resin 7 takes such a shape as being placed on a frame portion.Taking such a shape makes it possible to sufficiently ensure thecross-sectional area of a gate.

[0111] In a manner similar to the gate portion even in the case of airvent portions (E), each air vent is formed by a space between thetub-suspension lead 4 and the leads 3 disposed on both sides thereofover a predetermined length (b) as viewed from the edge of the package5. This is defined as a space which does not extend out beyond thethickness of the tub-suspension lead 4 and that of the lead 3. Thus, thethickness of the resin cured at the portion having the length (b), i.e.,the thickness of the air vent cured resin 9 coincides with the thicknessof the lead 3 or the tub-suspension lead 4 or smaller than that thereof.The thickness of the air vent cured resin 9 becomes identical to that ofeach resin burr 11 formed between the adjacent leads 3. Therefore, thefront and back sides thereof are both brought to flat surfacesrespectively. As a result, a trace of the air vent cured resin 9 is notprominent as compared with the resin burrs 11 while being designated atnumerals 9 in FIG. 3 and FIG. 1(a) in the semiconductor device 20according to the first embodiment. However, since each air vent isprovided outside the length (b) as a groove in the mold die, the airvent cured resin 9 distinctly exists on the leads in a state in whichthe lead frame 1 shown in FIGS. 1(a) and 1(b) is shown.

[0112] As shown in FIGS. 5 and 6, the semiconductor device 20 has a tub25 within the package 5. A semiconductor chip 27 is fixed to itscorresponding upper surface of the tub 25 with a jointing material 26interposed therebetween. The tub 25 is smaller than the semiconductorchip 27. The tub 25 has a structure where it is supported by the fourtub-suspension leads 4. Namely, the tub 25 and the tub-suspension leads4 are integrally formed.

[0113] Unillustrated electrodes formed on the surface of thesemiconductor chip 27, and inner ends of the leads 3 are respectivelyelectrically connected to one another by conductive wires 28. The tub25, semiconductor chip 27, and the wires 28 a are placed within thepackage 5. The means for electrically connecting the electrodes of thesemiconductor chip 27 and the leads 3 respectively may take anotherconfiguration.

[0114] When the tub-suspension leads 4 are used as external electrodeterminals, the ground electrode of the semiconductor chip 27 and thetub-suspension leads 4 may be connected to one another by the wires 28.

[0115]FIG. 7 is a cross-sectional view showing the mounting of asemiconductor device 20 on a wiring board or substrate 29. Lands 30 areprovided on one surface of the wiring board 29 in association with leads3 and tub-suspension leads 4 which serve as external electrode terminalsof the semiconductor device 20. Further, the leads 3 and thetub-suspension leads 4, which serve as the external electrode terminalsof the semiconductor device 20, are respectively superimposed on theselands 30 and electrically connected thereto with a bonding or jointingmaterial 31 interposed therebetween.

[0116] A description will next be made of a specific manufacture of asemiconductor device 20. FIG. 36 is a flowchart showing a method ofmanufacturing the nonleaded type semiconductor device, i.e., QFNaccording to the first embodiment. The semiconductor device 20 ismanufactured through respective process steps of Steps 101 through 106.

[0117] Namely, after the starting of work, the semiconductor device 20is manufactured through respective steps of chip bonding (S101), wirebonding (S102), molding (S103), plating (S104), and pinch-cut (S105) andlead tip cutting (S106) by composite cut molding, and its work is ended.

[0118] Upon the manufacture of the semiconductor device 20 according tothe first embodiment, such a matrix-configured lead frame 1 as shown inFIG. 9 is prepared. The lead frame 1 is configured in such a manner thatunit lead frame patterns 6 are arranged with 4 rows along an X directionand with 14 columns along a Y direction. Fifty-sixty semiconductordevices 20 can be fabricated from one sheet of lead frame 1. Guide holelands 35 a through 35 d used to transfer and position or locate the leadframe 1 are provided on both sides of the lead frame 1.

[0119] Upon a transfer mold, runners are located between the respectiverows. Thus, ejector pin holes 36 through which ejector pins are capableof extending, are provided to separate a runner cured resin from thelead frame 1. In order to separate a gate cured resin cured at a gateportion, which branches off the runners and flows into its correspondingcavity, from the lead frame 1, ejector pin holes 37 through the whichejector pins are capable of extending, are provided.

[0120]FIG. 10 is a plan view showing a unit lead frame pattern 6. Theunit lead frame pattern 6 is formed as a pattern having a frame portion2 shaped in the form of a rectangular frame, a plurality of leads 3extending inwardly from inside the respective sides of the frame portion2, and tub-suspension leads 4 which respectively extend inwardly of theframe portion from the four corners of the frame portion 2 and support acentral tub 25. The frame portion 2 has slits 38 intermittently providedat their sides in their side directions. Thus, the respective portionsof the frame portion 2 for supporting the leads 3 can be changedelastically.

[0121] A frame-portion corner (cornered portion) of the tub-suspensionlead 4, which faces the ejector pint hole 37, is defined as a pointwhere a gate (G) is located. Other three corners of the frame portion 2are defined as air vents (E) are located.

[0122]FIG. 14 is a diagram showing the unit lead frame pattern 6 and arecess defined in a parting face of one mold of a mold die. A squareportion having such edges as to cross portions lying in the course ofthe leads 3 is a cavity 40 for forming the package 5. Small rectangularportions of the upper right, lower right and lower left corners of theframe portion 2 correspond to air vent grooves 41, and the upper leftcorner of the frame portion 2 corresponds to a gate groove 42. A runnergroove or trench 43 is provided along the left side of the frame portion2. An ejector pint hole 36 is provided in the central portion of thewidth of the runner groove 42.

[0123] No groove for the air vent is provided in an area for a length(b) between the cavity 40 and each air vent groove 41. Air vent areas 44are respectively formed by areas surrounded by the tub-suspension leads4 at portions including the areas for the lengths (b), the adjacentleads 3 and the frame portions. An inner end of each air vent groove 41overlaps with its corresponding air vent area 44. Thus, air, which flowsout from the cavity 40, flows into each air vent groove 41 through suchair vent area 44.

[0124] No groove for the gate is provided in an area for a length (a)between the cavity 40 and the gate groove 42. Air vent areas 45 areformed by areas surrounded by the tub-suspension lead 4 at portionsincluding the area for the length (a), the adjacent leads 3 and theframe portions. An inner end of the gate groove 42 overlaps with itscorresponding gate areas 45. Thus, a resin, which flows into the gategroove 42, flows into the cavity 40 through such gate areas 45.

[0125] Further, the tub-suspension leads 4 are stepwise bent by onestage in the course thereof to elevate or lift the tube 25 upwardly.

[0126] The semiconductor device 20 is fabricated using such a lead frame1. Namely, as shown in FIG. 11, a semiconductor chip 27 is fixed ontoits corresponding tub 25 through an unillustrated bonding material (chipbonding: S101). Electrodes 46 of the semiconductor chip 27 and theircorresponding inner ends of leads 3 are electrically connected to oneanother by means of conductive wires 28 (wire bonding: S102).

[0127] Next, the lead frame 1 whose assembly has been finished, issingle-sided molded to form a package 5 (mold: S103). The single-sidedmolding is carried out by a transfer mold device. Referring to FIG. 13,the lead frame 1 in which the chip bonding and the wire bonding havebeen completed, is clamped onto a mold die 50 comprising a lower mold 51and an upper mold 52 of the transfer mold device.

[0128] As shown in FIG. 13, a parting face 52 a of the upper mold 52becomes flat and hence one surface of the lead frame 1 is closely bondedto the parting face 52 a. As described above, a cavity 40 for formingthe package 5, and an unillustrated runner groove, a gate groove 42 andan air vent groove 41 for guiding a resin melted in the cavity 40 areprovided in a parting face Sla of the lower mold 51.

[0129] In the parting face 51 a of the lower mold 51, the circumferenceof the periphery of the cavity 40 has a face 53 recessed by the samesize as the thickness of the lead frame 1, i.e., the thickness of eachof the leads 3 and the tub-suspension leads 4. Thus, the leads 3 andtub-suspension leads 4 are clamped onto the lower mold 51 and the uppermold 52 by the recessed face 53 and the parting face 52 a of the uppermold 52 in a closely contact state. Thus, the tub 25 and thesemiconductor chip 27 are kept in a floating state at the middle stageof the cavity 40.

[0130] By feeding a molten resin 55 via the runner groove and the gategroove 42, the resin 55 flows into the cavity 40 through a gate area 45.Air lying within the cavity 40 enters each air vent groove 41 through anair vent area 44 and escape from the cavity 40. With the escaping ofsuch air therefrom, the resin 55 also enters into the air vent areas 44and the air vent grooves 41.

[0131] Accordingly, the resin lying within the mold die 50 is curedaccording to the following resin cure processing (curing process). FIG.12 is a diagram of a resin cured portion as viewed in a mold-openedstate of the mold die 50.

[0132] As shown in FIG. 12, the package 5 is formed in the center of theunit lead frame pattern 6. A runner cured resin 10 formed within itscorresponding runner groove by curing exists on the left side of thepackage 5. A gate cured resin 7 formed within its corresponding gategroove 42 by curing exists on the left side. Air vent resins 9 formedwithin their corresponding air vent grooves 41 formed on the extensionsof the upper right, lower right and lower left cornered portions of thepackage 5 exist.

[0133] In FIG. 12, portions to which dots (matt spots) are applied,respectively correspond to resin portions, i.e., resin burrs 11 eachhaving the same thickness as each of the leads 3, the tub-suspensionleads 4 and the frame portion 2. The gate areas 45 and air vent areas 44exist on both sides of the four-cornered tub-suspension leads4 of thepackage 5. The gate cured resins 7 and the air vent cured resins 9 areformed inside their areas.

[0134] Next, a plating process is carried out (S104). The platingprocess is used upon implementation of the semiconductor device 20.Although not illustrated in the drawing, for example, a thickness ofabout 20 μm to about 30 μm is formed on the surface of each of the leads3 and the tub-suspension leads 4, which is exposed to the mountingsurface 21 of the package 5.

[0135] Next, as shown in FIG. 16, pinch-cut (SlO5) and lead tip cutting(S106) are carried out by a press machine. The pinch-cut (the cutting offour-cornered tub-suspension leads 4) and the lead tip cutting (thecutting of leads extending in the X/Y directions) are carried out by acomposite cut mold attached to the press machine.

[0136] The pinch-cut is as follows. As shown in FIG. 16, a lead frame 1is clamped between a die 15 a and a stripper 60 a. Four-corneredtub-suspension leads 4 and a gate cured resin 7 extended to both sidesof the tub-suspension lead 4, and air vent cured resins 9 arerespectively cut by die-punching using punches 16 a. The cut pieces 61 adrop in spatial portions of the die 15 a and are collected at apredetermined place by means of forced exhaust based on vacuumabsorption or the like.

[0137] Thus, the formation of the gate areas 45 and the air vent areas44, each of which falls within the thickness of each lead, makes itpossible to ensure an area to apply a die to lead surfaces on thepackage side and cut them from the mounting surface side of the leads bythe punches. The gate cured resins 7, which remain upon breaking andremoval of the gate cured resins 7, are assuredly held in the spatialportions of the pinch-cutting die 15 a even if they have variations insize to some extent. Therefore, the dies and punches at the cutting loseno stability due to the remaining gate cured resins 7.

[0138]FIG. 17 is a typical plan view showing dies 15 a and punches 16 a.FIG. 15 is a plan view showing a lead frame in which a tub-suspensionlead 4 and gate cured resins 7 placed on both sides of thetub-suspension lead 4, and tub-suspension leads 4 and air vent curedresins 9 placed on both sides of the tub-suspension leads 4 are cut.

[0139]FIG. 18 is a diagram showing a state in which a tub-suspensionlead 4 and gate cured resins 7 located on both sides of thetub-suspension lead 4 are cut by a die 15 a an a punch 16 a. At cutportions of the tub-suspension leads 4 at the base of the package 5, asshown in FIG. 18, the gate cured resins 7 are formed in a spacesurrounded by the tub-suspension leads 4, the leads 3 located on bothside of the tub-suspension leads 4, and the frame portion 2 with thesame thickness of each of the frame portion 2, tub-suspension leads 4and leads 3.

[0140] Since the obverse and reverse sides of each gate cured resin 7are flush with the front and back of each of the leads 3 and thetub-suspension leads 4 or the like and are protected and flattened, theoccurrence of resin waste can extremely be reduced. Since the gate curedresins 7 are cut in a state of being protected by the frame portion 2,the leads 3 and the tub-suspension leads 4, a resin crack is notproduced and does not extend deep within the package 5. Accordingly,moisture resistance of the package is also improved.

[0141] The lead tip cutting is divided into two process steps ofX-direction lead cutting and a Y-direction lead cutting in the case ofcomposite cut molding. Namely, the X-direction lead cutting is carriedout as shown in FIG. 20. A lead frame is clamped between a die 15 b anda stripper 60 b and each lead 3 extending along the X direction ispunched out by punches 16 b. Patterns for the die 15 b and the punches16 b are formed as shown in FIG. 21. The punched-out lead frame 1 isformed as shown in FIG. 19. Further, cut pieces 61 b drop into a spatialportion defined in the die 15 b and are thereafter collected at apredetermined location by means of forced exhaust based on vacuumabsorption or the like.

[0142] The Y-direction lead cutting is carried out as shown in FIG. 23.A lead frame 1 is clamped between a die 15 c and a stripper 60 c, andleads 3 extending along the Y direction are punched out by means ofpunches 16 c. Patterns for the die 15 c and the punches 16 c are formedas shown in FIG. 24. The punched-out lead frame 1 is formed as shown inFIG. 22. A package 5 at this stage is cut and separated from a frameportion 2 of the lead frame 1, so that a non-leaded type semiconductordevice (QFN) 20 is fabricated. Cut pieces 61 c drop into a spatialportion defined in the die 15 c and are collected at a predeterminedplace by means of forced exhaust based on vacuum absorption or the like.

[0143] The pinch-cut and lead tip cutting are carried out at the base ofthe package 5. For example, protruding lengths of the leads 3 and thetub-suspension leads 4 become 0.1 mm or less. Even in this case, theleading lines of the leads 3 and tub-suspension leads 4, and the cutlines of resin burrs 11, gate cured resins 7 and air vent cured resins 9linearly extend without being brought into irregularities respectively.

[0144]FIG. 25 is a cross-sectional view showing another semiconductordevice 20 fabricated by using a flat lead frame in which leads 3, a tub25 and tub-suspension leads 4 are placed on the same plane. FIG. 26 is abottom view of another semiconductor device. In such a structure, thetub 25 and the tub-suspension leads 4 are exposed to a mounting surface21 of a package 5 in their entirety. Therefore, when it is fixed to amounting or printed board such as a wiring board, the exposed surfacesof tub 25 and tub-suspension leads 4 serve as heat dissipation surfacesand hence it is of practical use that the heat of the semiconductor chip27 can be dissipated outside the package 5 rapidly. As a result, thesemiconductor device 20 can stably be operated.

[0145] When a plating film is provided on the surface of a lead frame ina lead frame state, the plating process shown in the flowchart shown inFIG. 8 becomes unnecessary.

[0146] According to the first embodiment, the following advantageouseffects are brought about.

[0147] (1) The cutting of leads 3 and tub-suspension leads 4 thatprotrude from the periphery of a package 5, and the cutting of gatecured resins 7 and air vent cured resins 9 produced upon the formationof the package 5 are performed while a die and punches are being appliedto portions respectively identical in thickness and whose front and backare flat. Thus, they can be cut by punches and a die without partlyapplying an on-cutting stress on the gate cured resins 7 and air ventcured resins 9 in a large way. It is therefore possible to reduce theoccurrence of resin waste 17 to a large extent as compared with theconventional cutting method.

[0148] (2) According to the above (1), since the resin waste 17 can beprevented from occurring, the attachment and crimping of the resin waste17 to lead surfaces serving as external electrode terminals due to thespattering of the resin waste 17, and the occurrence of flaws caused bythe crimping can be restrained. It is also possible to ensuresolderability at mounting and enhance mounting yields. Furthermore, thereliability of the mounting of a non-leaded type semiconductor device 20can be improved.

[0149] (3) According to the above (2), since a matrix type lead frametakes a structure wherein unit lead frame patterns 6 are vertically andhorizontally arranged in line, the prevention of the spattering of theresin waste 17 results in the prevention of contamination of the resinwaste 17 on each unit lead frame pattern 6 around a predetermined unitlead frame pattern 6, whereby production yields can be improved to agreat extent.

[0150] (4) According to the above (1), since the occurrence of the resinwaste 17 can be restrained, the contamination caused by the cut-dieresin waste 17 can be prevented from occurring, and the availabilityfactor of a press machine for mounting a cut die can be improved.

[0151] (5) Since the gate cured resins 7 and air vent cured resins 9around the package 5 are respectively identical to resin burrs 11 inobverse and reverse sides, it is difficult to visually confirm the gatecured resin 7 and air vent cured resins 9 on the periphery of thepackage 5 of the non-leaded type semiconductor device 20. Thus, thesemiconductor device is look good and preferable even in outerappearance, and increases in commodity property.

[0152] (6) The cutting of leads 3 and tub-suspension leads 4 thatprotrude from the periphery of a package 5, and the cutting of gatecured resins 7 and air vent cured resins 9 produced upon the formationof the package 5 are performed at portions respectively identical inthickness and whose front and back are flat. Thus, they can be cut bypunches and a die without partly applying an oncutting stress on thegate cured resins 7 and air vent cured resins 9 in a large way.Therefore, such a resin crack as to extend toward the inside of thepackage 5 is not produced. As a result, no moisture enters the package 5through the resin crack. Further, the package 5 increases in moistureresistance, and production yields are enhanced.

[0153] (7) According to the above (2) through (4) and (6), themanufacturing cost of a semiconductor device can be reduced in terms ofhigh productivity and an improvement in yield. For example, the yield isimproved about 0.5%.

[0154] (Second Embodiment)

[0155]FIGS. 27 through 29 are respectively diagrams showing a method ofmanufacturing a semiconductor device according to another embodiment(second embodiment) of the present invention, wherein FIG. 27 is atypical cross-sectional view showing a transfer mold state, FIG. 28 is atypical plan view showing a single-sided molded lead frame, and FIG. 29is a typical cross-sectional view showing a state in which gate curedresins, air vent cured resins and tub-suspension leads overlapping withthese are cut.

[0156] The second embodiment is different from the first embodiment inthat as shown in FIG. 27, a gate 70 having a width d and air vents 71each having a width e are provided even on tub-suspension leads 4 at aresin injection place (G) and air vent places (E) corresponding torespective corners of a frame portion 2. The thickness of each of thegate 70 and the air vents 71 is made thinner by about f than thethickness of each of leads 3 and the tub-suspension leads 4. Thethickness f ranges from about 20 μm to about 30 μm, for example, andserves as a flat surface.

[0157] Incidentally, the gate 70 and the air vents 71 may differ ingroove depth. In this case, the bottom of each groove is made flat so asnot to cause resin waste in a subsequent step.

[0158] The gate 70 is wider than the width of each tub-suspension lead4, and overlaps with a gate area 45 on both sides of the tub-suspensionleads 4 and is in communication therewith. Further, each of the airvents 71 is wider than the width of the tub-suspension lead 4, andoverlaps with its corresponding air vent area 44 on both sides of thetub-suspension leads 4 and is in communication therewith. As a result, agate cured resin 7 a having a width d is formed between a package 5 anda gate cured resin 7 in a state of a post-transfer mold lead frame 1 asshown in FIG. 28. Further, air vent cured resins 9 a each having a widthe are respectively formed between the package 5 and air vent curedresins 9.

[0159] The cutting of the gate cured resin 7 a and the tub-suspensionlead 4 superposed thereon, and the cutting of the air vent cured resins9 a and the tub-suspension leads 4 superposed thereon are carried out bya die 15 a and punches 16 a as shown in FIG. 29 in a manner similar tothe first embodiment.

[0160] Since portions of the gate cured resin 7 a and the air vent curedresins 9 a, which make contact with the die 15 a and are supportedthereby, are flat even in the case of such cutting, it is hard to causeresin waste and a resin crack in a manner similar to the firstembodiment.

[0161] Incidentally, the gate width d and the air vent widths e may beset larger than the width of each tub-suspension lead 4 and connected tothe gate area 45 and the air vent areas 44 to thereby less reduceresistance at resin injection.

[0162] Incidentally, the alignment of the heights of the gate curedresin 7 a and the air vent cured resins 9 a formed on the four-corneredtub-suspension leads 4 makes it possible to carry out pinch-cut stabler.

[0163] It is possible to prevent the occurrence of the resin waste andthe resin crack and achieve an improvement in yield even in the case ofthe second embodiment in a manner similar to the first embodiment.

[0164] (Third Embodiment)

[0165]FIG. 30 is a typical plan view showing a lead frame portionsingle-sided molded by a method of manufacturing a semiconductor deviceaccording to a further embodiment (third embodiment) of the presentinvention. The present invention is a method of avoiding thesuperimposition of a gate and air vents on tub-suspension leads 4.Namely, in FIG. 30(a), the gate is provided so as to intersect a frameportion 2 to thereby cause its leading end to communicate with a gateregion or area 45. Further, air vents are respectively provided so as tointersect the frame portion 2 to thereby cause their leading ends tocommunicate with their corresponding air vent regions or areas 44.

[0166] In FIG. 30(b), a gate is provided so as to cross or intersect aframe portion 2 to thereby cause its leading end to communicate withspaces defined between tub-suspension leads 4 and leads 3 and spacesdefined between the adjacent leads 3. Further, air vents arerespectively provided so as to intersect the frame portion 2 to therebycause their leading ends to communicate with spaces defined betweentheir corresponding tub-suspension leads 4 and leads 3 and spacesdefined between their corresponding adjacent leads 3.

[0167] Thus, inner ends of a gate and air vents based on or related togrooves defined in a parting surface of a mold die are respectivelyspaced predetermined distances from edges of a cavity 40 for forming apackage 5. This spacing is provided in such a manner that spacingdefined by surfaces of upper and lower molds of the mold die, which areflush with the obverse and reverse sides of the leads 3 andtub-suspension leads 4, and side faces of the adjacent leads 3 or sidefaces of the leads 3 and tub-suspension leads 4 is used as a resin flowpath.

[0168] It is possible to prevent the occurrence of resin waste and aresin crack and achieve an improvement in yield even in the case of thethird embodiment in a manner similar to the first embodiment.Incidentally, the layout of the gate and the air vents is not limited toones shown in FIG. 30.

[0169] While the invention made above by the present inventors has beendescribed specifically by the illustrated embodiments, the presentinvention is not limited to the above-described embodiments. It isneedless to say that various changes can be made thereto within thescope not departing from the substance thereof. For instance, thepresent invention can similarly be applied even to an SON wherein leadsused as external electrode terminals are exposed to both sides of amounting surface of a package, and a similar effect can be broughtabout. The present invention can be applied to at least the non-leadedtype semiconductor device.

[0170] In the present invention, the adoption of a sheet mold methodmakes it possible to more suitably set an exposed shape of eachelectrode on the back of a package. The present sheet mold method is thetechnology of, when a lead frame is interposed between an upper mold anda lower mold, interposing a flexible resin sheet between the lower moldand the lead frame, and sealing each electrode portion of the lead framein particular with a resin by means of a clamping or pinch-holding forceof a die in a state in which the electrode portion has been cut into thesheet, thereby offsetting the back of the package with respect to amounting surface of the electrode. When such a method is adopted, theback of the gate cured resin 7 is also offset from the back of eachlead. Therefore, when the sheet mold method is applied to theembodiments of the present invention, the thickness of the gate curedresin might be smaller than that of the lead frame.

[0171] While the present embodiment has described the structure whereinthe tub-suspension leads 4 are exposed from the corners of the package,the invention is not limited to such a type that the tub-suspensionleads 4 are exposed at the package corners. The invention may be appliedto, for example, a case where the tub-suspension leads 4 are notprovided, and a case where the tub-suspension leads 4 are formed atportions other than the corners. In this case, the gate region or area45 may be provided between the adjacent external electrode terminals(leads).

[0172] Advantageous effects obtained by typical ones of the inventionsdisclosed in the present application will be described in brief asfollows:

[0173] (1) Since the occurrence of resin waste and a resin crack can berestrained when a gate cured resin and air vent cured resins employed inthe manufacture of a nonleaded type semiconductor device are cut, animprovement in production yield and an improvement in the quality of aproduct can be achieved.

[0174] (2) Since the occurrence of resin waste and a resin crack can berestrained when a gate cured resin and air vent cured resins employed inthe manufacture of a nonleaded type semiconductor device are cut, it ispossible to prevent a reduction in availability factor of a cuttingdevice or the like due to the resin waste and reduce the manufacturingcost of the semiconductor device.

1. A semiconductor device comprising: an encapsulater comprising aninsulating resin, lead exposed to a mounting surface of saidencapsulater and a gate cured resin which remains as a result to formsaid encapsulater; wherein said gate cured resin exists in a portionbetween the adjacent leads with a thickness identical to or smaller thanthe thickness of said each lead.
 2. A semiconductor device comprising:an encapsulater comprising an insulating resin, lead and tub-suspensionleads exposed to a mounting surface of said encapsulater and a gatecured resin which remains as a result to form said encapsulater; whereinsaid gate cured resin exists in a portion between said eachtub-suspension lead and said lead with a thickness identical to orsmaller than the thickness of said each tub-suspension lead.
 3. Asemiconductor device comprising: an encapsulater comprising aninsulating resin, leads and tub-suspension leads exposed to a mountingsurface of said encapsulater and a gate cured resin and air vent curedresins which remains as a result to form said encapsulater; wherein eachof said gate cured resin and said air vent cured resins exists in aportion between said each tub-suspension lead and said lead with athickness identical to or smaller than the thickness of each of resinburrs.
 4. A semiconductor device comprising: an encapsulater comprisingan insulating resin, leads and tub-suspension leads exposed to amounting surface of said encapsulater and a gate cured resin and airvent cured resins which remains as a result to form said encapsulater;wherein said gate cured resin and said air vent cured resinsrespectively extend from the edges of said encapsulater with apredetermined thickness and have obverse and reverse sides formed asflat surfaces.
 5. The semiconductor device according to claim 4, whereinsaid gate cured resin partly overlaps with said tub-suspension lead. 6.The semiconductor device according to claim 4, wherein said air ventcured resins partly overlap with said tub-suspension leads respectively.7. The semiconductor device according to claim 4, wherein said gatecured resin partly overlaps with at least one lead.
 8. The semiconductordevice according to claim 4, wherein said air vent cured resins partlyoverlap with at least one lead.
 9. A method of manufacturing asemiconductor device, comprising the steps of: preparing a lead framehaving a frame portion, a plurality of leads which protrude inwardly inthe frame portion from the frame portion, and a plurality oftub-suspension leads which protrude inwardly in the frame portion fromthe frame portion and support a tub at leading end portions thereof;fixing a semiconductor chip to one surface of the tub; electricallyconnecting electrodes of the semiconductor chip and the leads; coveringthe semiconductor chip and the leads with an encapsulater comprising aninsulating resin and exposing the leads and the tub-suspension leads toa mounting surface of the encapsulater; and cutting the leads and thetub-suspension leads, wherein a vertical space defined by only the sidesof the leads and the tub-suspension leads is used as a resin flow pathto form the encapsulater, and the leads and the tub-suspension leads arecut at a resin portion cured in the vertical space defined by only thesides of the leads and the tub-suspension leads.
 10. The methodaccording to claim 9, wherein a gate provided in a mold die is providedoutside the vertical space defined by only the sides of the leads andthe tub-suspension leads, and a resin passes through the gate and flowsthrough the vertical space to thereby form the encapsulater.
 11. Themethod according to claim 9, wherein air vents defined in the mold dieare provided outside the vertical space defined by only the sides of theleads and the tub-suspension leads, and the resin passes through thevertical space and goes through the air vents.
 12. A method ofmanufacturing a semiconductor device, comprising the steps of: preparinga lead frame having a frame portion, a plurality of leads which protrudeinwardly in the frame portion from the inside of the frame portion, anda plurality of tub-suspension leads which protrude inwardly in the frameportion from the inside of the frame portion and support a tub atleading end portions thereof; fixing a semiconductor chip to one surfaceof the tub; electrically connecting electrodes of the semiconductor chipand the leads; covering the semiconductor chip and the leads with anencapsulater comprising an insulating resin and exposing the leads andthe tub-suspension leads to a mounting surface of the encapsulater; andcutting the leads and the tub-suspension leads, wherein a vertical spacethicker than the thickness of each of the leads and the tub-suspensionleads is used as a resin flow path to form the encapsulater, and theleads and the tub-suspension leads are cut at a resin portion cured inthe vertical space thicker than the thickness of each of the leads andthe tub-suspension leads.
 13. The method according to claim 12, whereina gate provided in a mold die is provided outside the vertical spacethicker than the thickness of each of the leads and the tub-suspensionleads, and a resin passes through the gate and flows through thevertical space to thereby form the encapsulater.
 14. The methodaccording to claim 12, wherein air vents defined in the mold die areprovided outside the vertical space thicker than the thickness of eachof the leads and the tub-suspension leads, and the resin passes throughthe vertical space and goes through the air vents.
 15. The methodaccording to claim 12, wherein a matrix type lead frame in which unitlead frame patterns are vertically and horizontally arranged in line, isprepared as the lead frame.
 16. The method according to claim 12,wherein said lead frame is given solder plating used for its mounting.